Adjust default_print() to not run over snapend.

Adjust default_print() to not run over snapend.

Kill default_print_unaligned() and adjust default_print() to also work
with unaligned buffers. There is no need for two functions doing the
same thing.

Pass the right length in nsh_print to default_print(). Fixes on place
that makes tcpdump crash.
Reported by Peter J. Philipp (pjp at delphinusdns dot org)
OK mbuhl@